/**
 * Copyright (c) 2011-2017, James Zhan 詹波 (jfinal@126.com).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.jfinal.template.stat.ast;

import java.io.Writer;
import com.jfinal.template.Env;
import com.jfinal.template.TemplateException;
import com.jfinal.template.stat.Location;
import com.jfinal.template.stat.ParseException;
import com.jfinal.template.stat.Scope;
import com.jfinal.template.expr.ast.Expr;
import com.jfinal.template.expr.ast.ExprList;
import com.jfinal.template.expr.ast.Id;

/**
 * Define 定义模板函数：
 * #define funcName(p1, p2, ..., pn)
 *   body
 * #end
 * 
 * 模板函数类型：
 * 1：全局共享的模板函数
 *   通过 engine.addSharedFunction(...) 添加，所有模板中可调用
 * 2：模板中定义的局部模板函数
 *   在模板中定义的模板函数，只在本模板中有效
 * 
 * 高级用法：
 * 1：局部模板函数可以与全局共享模板函数同名，调用时优先调用模板内模板数
 * 2：模板内部不能定义同名的局部模板函数
 */
public class Define extends Stat {
	
	private static final String[] NULL_PARAMETER_NAMES = new String[0];  // 空参数类型数组
	
	private String functionName;  // 共享function名称
	private String[] parameterNames;  // 参数名称集
	private Stat stat;  // template文件信息结构类
	
	public Define(String functionName, ExprList exprList, Stat stat, Location location) {
		
		setLocation( location );
		
		this.functionName = functionName;  // template共享function
		this.stat = stat;
		
		Expr[] exprArray = exprList.getExprArray();
		if ( exprArray.length == 0 ) {
			this.parameterNames = NULL_PARAMETER_NAMES;
			return ;
		}
		
		parameterNames = new String[exprArray.length];  // 参数名称集
		for ( int i = 0; i < exprArray.length; i++ ) {
			if ( exprArray[i] instanceof Id ) {
				parameterNames[i] = ((Id)exprArray[i]).getId();
			} else {
				throw new ParseException( "The parameter of template function definition must be identifier", location );
			}
		}
	}
	
	public String getFunctionName() {
		return functionName;
	}
	
	public String[] getParameterNames() {
		return parameterNames;
	}
	
	/**
	 * Define 的继承类可以覆盖此方法实现一些 register 类的动作
	 */
	public void exec(Env env, Scope scope, Writer writer) {
		
	}
	
	/**
	 * 真正调用模板函数
	 */
	public void call(Env env, Scope scope, ExprList exprList, Writer writer) {
		
		if ( exprList.length() != parameterNames.length ) {
			throw new TemplateException( "Wrong number of argument to call the template function, right number is: " + parameterNames.length, location );
		}
		
		scope = new Scope( scope );
		if ( exprList.length() > 0 ) {
			
			Object[] parameterValues = exprList.evalExprList( scope );  // 对所有表达式求值，并返回所有表达式的值
			for ( int i = 0; i < parameterValues.length; i++ ) {
				scope.setLocal( parameterNames[i], parameterValues[i] );  // 参数赋值
			}
			
		}
		
		stat.exec( env, scope, writer );
		scope.getCtrl().setJumpNone();  // #define 中的 return、continue、break 全部在此消化
	}
	
	public String toString() {
		
		StringBuilder ret = new StringBuilder();
		ret.append( "#define " ).append( functionName ).append( "(" );
		
		for ( int i = 0; i < parameterNames.length; i++ ) {
			
			if ( i > 0 ) {
				ret.append( ", " );
			}
			
			ret.append( parameterNames[i] );
		}
		
		return ret.append( ")" ).toString();
	}
	
	// -----------------------------------------------------------------------
	/**
	 * envForDevMode 属性性以及相关方法仅用于 devMode 判断当前 #define 指令所在资源是否被修改
	 * 仅用于 EngineConfig 中处理 shared function 的逻辑
	 */
	private Env envForDevMode;
	
	public void setEnvForDevMode(Env envForDevMode) {
		this.envForDevMode = envForDevMode;
	}
	
	public boolean isSourceModifiedForDevMode() {
		
		if ( envForDevMode == null ) {
			throw new IllegalStateException( "Check engine config: setDevMode(...) must be invoked before addSharedFunction(...)" );
		}
		
		return envForDevMode.isStringSourceListModified();
	}
}



